Charge forming means



Dec. 3,

J. DOLZA CHARGE FORMING MEANS Original Filed June 5, 1957 ATTORI/EKUnited States Patent O 25,492 CHARGE FORMING MEANS John Dolza, Fenton,Mich., assigner to General Motors Corporation, Detroit, Mich., acorporation of Deln- Matter enclosed in heavy brackets appears in theoriginal patent but forms no part of this reissue specification; matterprinted in italics indicates the additions made by reissue.

The present invention relates to internal combustion engines and moreparticularly to the charge forming means therefor.

`In the operation of .an internal combustion engine of the so-calledspark ignite-d variety the combustible charge of air and fuel may beformed in the induction system and then introduced into the enginecylinders where it is burned. One means for accomplishing this is toprovide an air induction system for supplying the air to the cylindersand a fuel injection system for injecting metered quantities of fuelinto the charge. The injection system may include a fuel metering valvethat is actuated in response to the fuel demands of the engine. Forexample, this valve may be operatively interconnected with a diaphragmresponsive to a Vacuum signal developed in the throat of a venturilocated in the air induction system. ln order to insure an accuratemetering action the venturi must have a sufficient restriction to insurethe development o-f a vacuum signal of adequate strength and accuracyeven during the small air flows occurring during light load operation.Iif the engine operates over a very wide range of loads such as anautomotive engine, if the venturi presents a sufficient restriction todevelop a satisfactory signal during idle operation, during heavy loadoperation it will restrict the volume of air entering the engine,thereby limiting the volumetric efciency of the engine and therefore itsmaximum power.

`It is now proposed to provide a fuel injection system having means fordeveloping a signal of adequate strength even at light loads withoutmaterially limiting the volumetric etiiciency of the induction system.More particulariy, this is to be accomplished by providing a pluralityof venturis in the induction system which are arranged to becomeoperative in sequence. Thus a small venturi may be provided for useduring the light load range and a large venturi may be provided for usein the heavy load range. The throat of each venturi is interconnectedwith a separate diaphragm each of which is, in turn, interconnected withthe fuel metering valve by a common linkage system effective to transmitthe force from each diaphragm to the metering valve. Thus, irrespectiveof the manner in which the air flow divides between the venturis, theresultant force on the metering valve will always be a function of thetotal amount of air flow and the fuel will thus always be accuratelymetered.

In the one sheet of drawings:

The FIGURE is a diagrammatic view of a fuel injection system embodyingthe present invention.

Referring to the drawings in more detail, the present invention may beincorporated into a fuel injection system for use on any suitablemulticylinder internal combustion engine 12. In the present instance thesystem 10 is employed on a so-called spark ignited engine 12 having aninduction system 14 that includes an atmospheric air intake 16 and aplurality of induction passages 18 `that are interconnected with theintake 16 by a suitable manifold (not shown) and terminate in thecombustion chambers Reissued Dec. 3, 1963 ICC 20 for supplying thecharge thereto. The air flow into the cylinders is controlled by theintake valves 22.

The intake 16 includes at least two venturis 24 and 26 through which theinduction air flows. The primary venturi 24 is particularly designed toproduce an accurate metering signal during the low speed while thesecondary venturi 26 is arranged to supply additional air during heavyloads with a minimum iiow resistance. The flow of air through eachventuri 24 an-d 26 is regulated by a primary throttle 28 and a secondarythrottle 30. These throttles 28 and 30 are manually actuated by alinkage 31 that will cause only the primary throttle 2S to open duringlight loads but will permit both throttles to open at full loads.

The fuel system 10 includes a fuel storage tank 32, fuel pumping means34 for circulating the fuel through the system 10, a metering mechanism36 for maintaining the fuel flow in the desired proportions to the airow, and a plurality of nozzles 38 located in the induction passages 18adjacent the intake valves 22 and interconnected with metering mechanism36 by injector lines 4t) for discharging the atomized metered fueldirectly into the air as it flows to the cylinders. The pumping means 34may be of any desired design that is capable of delivering a surplus offuel at a pressure in excess of that required to operate the system 10.

The metering mechanism 36 includes a housing 42 having a fueldistributor and regulator 44 in the bottom thereof and a pair ofdiaphragm chambers 46 and 48 in the top thereof. The fuel distributorand regulator 44 includes an outlet 49 with a flow control valve 51therein, a distributor chamber 50 and an inlet 52 which may be connectedto the pump means. The identical injector lines 4i) may radiateoutwardly from the center of the distributor chamber with the outer endsthereof including nozzles located in the induction passages and aimed todirect a stream of fuel toward the intake valves. The inlet 52 isconnected to the bottom of the vertical distribution chamber 50 so thatthe fuel from the inlet 52 will How vertically upwardly through thedistribution chamber 50 and leave through the outlet 49 or the injectorlines 40. It has been found desirable to provide a strainer or filterelement 54 in the inlet 52 for removing any impurities that mightotherwise impair the operation of the system 1t), and also to provide apressure relief valve 56 to maintain the fuel pressure anterior theretoin excess of some predetermined amount.

In order to obtain a uniform distribution of the fuel to all of thecylinders, it is desirable that the hydraulic resistances of the nozzies38 be considerably larger than that of the injector lines 40. Thus theprimary factor controlling the quantity of fuel iiow will be the nozzles38 and any minor irregularities in the injector lines will have littleor no effect on the metering and distribution of fuel to the cylinders.These nozzles 38 are preferably similar to those disclosed in copendingapplication Serial No. 608,893 Dolza, rst filed September 10, 1956, nowPatent No. 2,860,859, wherein the fuel is discharged through a smallorifice disposed in an envelope of air at substantially atmosphericpressure provided by vent 58. The orifice is aimed to direct a stream offuel through a second opening and into the induction system toward theintake valves 22. It may thus be seen that the fuel system 10 will besubstantially isolated from the effects of intake vacuum. Theresistances of the small orifices and the injector lines will present aresistance to the ow of fuel that will cause a pressure in `thedistributor chamber that will be indicative of the amount of meteredfuel injected into the charge.

A piston type fuel control valve 51 may be disposed in the outlet 49 atthe top of the distributor chamber 50 for regulating the amount of spillfuel bypassed from the distributor chamber and returned to the fuelstorage tank 32. lt will be seen that since the valve S1 controls theamount of spill fuel, it will also regulate or meter the amount of fuelilow through the nozzles 33. In the present instance this valve 51comprises a piston 6) slidably disposed in la vertical bore with thelower end thereof reciprocating into and out of outlet opening 49. Thusthis axial movement will vary the effective area of the opening andthereby regulate the fuel flow. Since the cross-sectional area of thepiston 60 will be exposed to the pressure of the fuel in the distributorchamber Sl) which is a function of the amount of metered fuel flowingthrough the nozzles, the resultant upward force on the piston 60 tendingto `lift it out of the oulet 49 will also be indicative of the amount ofmetered fuel.

Each of the diaphragm chambers 46 and 48 includes a ilexible diaphragm62 or 64 that extends horizontally thereacross to divide each chamber4-6 and 48 into an upper compartment 66 and 68 and a lower compartment70 and 72. Although the upper compartments 66, 68 may be vented directlyto atmosphere, it is preferable that a housing 67 be formed over thelinkage 78 and that the interior 69 of the housing 67 be interconnectedwith the intake 16 anterior to the venturis 24, 26 by a tube 71. Thelower compartment 70 is preferably connected to the throat of theprimary venturi 24 by a primary signal line 74 an dthe lower compartment72 is connected to the throat of the secondary venturi 26 by a secondarysignal line 76. It may thus be seen that as the air flows through theprimary venturi 24 and a vacuum develops in the throat, the diaphragm 62will have a force thereon indicative of the quantity of air flowingthrough that venturi 24 and that when the air is also flowing throughthe secondary venturi 26, the vacuum in the secondary throat will createa force on the secondary diaphragm 64 indicative of the quantity of airflowing through the secondary venturi 26. The primary diaphragm 62 maybe connected to the control valve 51 by a linkage 78 that will transferthe force on the diaphragm to the piston 601. Although this linkage 78may be of any suitable form in the present instance it includes a lever80 that has a fulcrum 82 in the middle and a vertical link 84 on the end81 that is connected to the joint 86 between a counterweight lever 88and a control lever 90. The counterweight lever 88 may pivot about afixed pin 92 and have a weight on the end thereof that will tend tobalance the weight of the various portions of the linkage system. Thecenter of the control lever 90 pivots about the lower end of anadjustable ratio arm 93 while the end thereof bears on the piston 60.Thus it will be seen that the difference in air pressure on thediaphragm 62 will produce a downward force on the piston 60 that willbias it closed in opposition to the opening force of the fuel pressurein the distributor chamber 50. The secondary diaphragm 64 is alsointerconnected with the piston valve 60 by means of a second lever 94that pivots on its own fulcrum 96 and has one end connected to thevertical link 84. Thus any air flowing through the secondary venturi 26will also impose an additional force on the piston valve 60 that willtend to close in proportion to the secondary air flow.

As p-reviously stated the position of the piston 60 in the outlet 49regulates the volume of bypassed fuel and thereby controls or meters theamount of fuel distributed to the various cylinders. The fuel pressureinside of the distributor chamber 50 will exert an upward force on thebottom of the piston 60 which will tend to raise the same therebyincreasing the amount of fuel bypassed and decreasing the flow ofmetered fuel. However, the forces produced by the air flows through theprimary and secondary venturis 24 and 26, will tend to force the piston60 downwardly into the outlet and increase the supply of the fuel to thecylinders. '1 nus it may be seen that the air flow and fuel flow willproduce forces opposing each other and cause movement of the piston 60until the two forces are balanced. When these two forces are balancedthe air and fuel will be flowing in some predetermined ratio. Theproportions of this ratio will be determined by the areas of thediaphragms 6-2 and 64, the area of the piston 60 exposed to the fuelpressure, and the mechanical advantages of the linkage and levers, etc.Preferably, the diaphragms 62 and 64, venturis 24 and 26 and levers 8i)and 94 are proportional so that a given unit of air flow will p-roducethe same force on the piston 60 irrespective of whether it flows throughthe primary or secondary venturi 24 or 26.

It can be appreciated that by rocking `the ratio arm 93 about the shaft98, the mechanical advantage of the linkage can be varied so that theamount of the force transferred from the diaphragms 62 and 64 to thepiston 60 can be readily adjusted. This will, in turn, permit aconvenient means of adjusting the air-fuel ratio` However, it is, ofcourse, apparent that there are numerous other means that may be used`with or in place thereof for regulating the air-fuel ratio in anydesired manner.

It may therefore be seen that a simple and economical fuel injectionsystem has been provided which is particularly adapted for supplyingfuel to an internal combustion engine operating over a wide range ofloads. This system will insure an accurate metering action during lightloads and at the same time will not restrict the volumetric efficiencyduring heavy loads.

lt is to be understood that, although the invention has been describedwith specific reference to a particular embodiment thereof, it is not tobe so limited since changes and alterations therein may be made whichare within the full intended scope of this invention as defined by theappended claims.

The claims:

l. Charge forming means for an internal combustion engine comprising afuel valve adapted to meter the fuel tlow, a plurality of inductioninlets adapted to draw induction air from the atmospher a metering meansin each of said inlets for creating a pressure differential indicativeof the air flow therethrough and separate means responsive to each ofsaid differentials for actuating said valve in response thereto.

2. Charge forming means for an internal combustion engine comprising abypass valve for metering the fuel llow and being responsive to anopening force proportional to said flow, an induction inlet having apair of parallel venturis with throats therein, a pressure sensitivemeans responsive to the pressure in the throat of each venturi forimposing separate closing forces on said valve in opposition to saidfuel force.

3. Charge forming means for an internal combustion engine comprising abypass valve adapted to meter fuel by passing the surplus fuel, saidvalve being responsive to a .uel pressure tending to open said valvewith a force indicative of the amount of metered fuel, an inductioninlet having a primary venturi and a secondary venturi, means responsiveto the air flow through said primary venturi for imposing a primaryclosing force on said valve indicative of said llow and means responsiveto the air llow through said secondary venturi for imposing a secondaryclosing force on said valve indicative of said secondary flow.

4. Charge forming means for an internal combustion engine comprising abypass valve adapted to meter fuel by bypassing `the surplus fuel, saidvalve being responsive to a fuel pressure tending to open said valvewith a force indicative of the amount of metered fuel, an inductioninlet having `a pair `of parallel metering means therein, a throttlevalve posterior to each of said means for separately controlling theflow of `air therethrough, means responsive to the air flow through oneof said first means for imposing a primary closing force on said fuelvalve indicative of said ow 'and means responsive to the air ow throughthe other of said first means for imposing a secondary closing force onsaid fuel valve indicative of an air ow therethrough.

5. Charge forming means for an internal combustion engine comprising abypass valve `adapted to meter fuel by bypassing the surplus fuel, saidvalve being responsive to a fuel pressure tending to open said valvewith a force indicative of the amount of metered fuel, an inductioninlet having a primary venturi and a secondary venturi, separatethrottle valves in each of said venturis, means responsive to the `airow through said venturis for irnposing a primary closing force on saidbypass valve indicative of said air flows.

6. Charge forming mean-s for an internal combustion engine comprising abypass valve adapted to meter fuel by bypassing the surplus fuel, saidvalve being responsive to a fuel pressure tending to open said valvewith a force indicative of the amount of metered fuel, an inductioninlet having a primary venturi and a secondary venturi in parallelthereto, a first diaphragm responsive to the amount of 'air flow throughsaid primary venturi for imposing a primary closing force on said fuelvalve indicative of said air flow and `a second diaphragm responsive tothe air How through said secondary venturi for imposing a secondaryclosing force on said fuel valve indicative of said secondary flow.

7. Charge forming means for an internal combustion engine comprising adistributing chamber adapted to receive fuel under pressure anddistribute metered fuel to the cylinders of said engine, a bypass valvein said distributing chamber adapted to meter fuel by bypassing thesurplus fuel therefrom, the fuel pressure in said chamber beingindicative of the amount of metered fuel and tending to open said bypassvalve with a `force proportional thereto, an induction inlet having apair of parallel metering restrictions therein, means responsive to theair oW through one of said restrictions for imposing a primary closingforce on said bypass valve indicative of said air flow, means responsive`to the air ow through the other of said restrictions for imposing asecondary closing force on said bypass valve indicative of said secondair fiow.

8. Charge forming means for an internal combustion engine comprising adistributing chamber `adapted to receive fuel under pressure anddistribute metered fuel to the cylinders of said engine, a bypass valvein said distributing chamber adapted to meter fuel by bypassing thesurplus fuel therefrom, the fuel pressure in said chamber beingindicative of the amount of metered fuel and tending to open said bypassvalve with a force proportional thereto, an inlet having a primaryventuri and a secondary venturi, means responsive to the air flowthrough said primary venturi for imposing a closing force on said valveindicative of said flow and means responsive to the air flow throughsaid secondary venturi for imposing a secondary closing force on saidbypass valve indicative of said secondary ow.

9. The combination of claim 5 wherein said last mentioned means includeVa pair of diaphragms each of which is responsive to the pressuredifferential in one of said venturis and is operatively interconnectedwith said valve by a control linkage.

10. Charge forming means for an internal combustion engine comprising adistributing chamber adapted to receive fuel under pressure anddistribute metered fuel to the cylinders of said engine, a bypass valvein said distributing chamber adapted to meter fuel by bypassing thesurplus fuel therefrom, the fuel pressure in said chamber beingindicative of the amount of metered fuel and tending to open said bypassvalve with a force proportional thereto, an induction system having `aninlet with a primary venturi and a secondary venturi in parallelthereto, a first diaphragm responsive to the amount of air flow throughsaid primary venturi operatively interconnected with said bypass valveby a linkage adapted to exert a closing force on said valve indicativeof said air ow, a second diaphragm responsive to the amount of air flowthrough said secondary venturi operatively interconnected with saidlinkage for imposing a secondary closing force on said bypass valveindicative of said secondary air ow.

1l. The combination of claim l0 including enrichment means adapted tomodify the effectiveness of said forces to thereby control the air-fuelratio.

12. The combination of claim 10 wherein said linkage includes a leverwith an adjustable `fulcrum for changing the mechanical advantage ofsaid forces to thereby regulate the air-fuel ratio.

13. Charge forming means for a multicylinder internal combustion enginecomprising ian induction system for supplying air to said cylinders andincluding a plurality of atmospheric inlets, each of which includesmeans for creating a pressure differential indicative of the air flowtherethrough, a fuel metering valve responsive to a force indicative ofthe amount of fuel flow and effective to meter the fuel ow to thecylinders, means responsive to said pressure differentials for imposinga force on said valve indicative of the air ow therethrough.

14. A fuel metering system for an internal combustion engine comprisingprimary and secondary air intake conduits, air flow metering means ineach said air conduit, fuel conduit means communicating with a fuelsupply and said engine, and pressure responsive adjustable fuel meteringmeans in said fuel conduit means adjustable to vary the flow of fueltherethrough, said fuel metering means being operatively connected toeach said air flow metering means in each said air conduit andadjustable thereby in response to air flow through each said airconduit, said metering means in said secondary air intake conduitbecoming active to adjust said fuel metering means upon a predeterminedair flow in said primary nir intake conduit.

15. A mass flow responsive fuel control system for an internalcombustion engine comprising primary and sccondary air intake conduitsadapted to bc operatively connected to said engine, air flow meteringmeans in each of said conduits, constant delivery fuel feed means forsupplying fuel to said engine, return flow means connected to said feedmeans to purge fuel vapors therefrom, pressure responsive adjustablefuel metering means in said return flow means for regulating the flowtherethrough, said fuel metering means being operatively connected toeach said air flow metering means und adjustable thereby to regulate theflow of fuel to the engine in linear proporportion to the air flowthereto.

16. A mass flow responsive fuel control system for an internalcombustion engine comprising primary and sccondary air intake conduitsadopted to be operatively connected to said engine, air How meteringmeans in each said conduit, constant delivery fuel fccd means forsupplying fuel to said engine, return flow means connected to said fuelfeed means to purge fuel vapors therefrom, pressure responsiveadjustable fuel metering means in said return flow means for regulatingthe flow therethrough, said fuel metering means comprising u shiftnblemember connected to two nir pressure responsive diaphragm devices, sniddiaphragm devices being connected to said air flow metering means insaid air intake conduits and responsive to air flow through said airintake conduits to adjust said fuel metering means to regulate the flowof fuel to the engine in linear proportion to the air flow thereto.

17. A fuel metering unit for an internal combustion engine comprising aprimary und a secondary air conduit for supplying air to said engine, aventuri tube in cach said air Conduit for measuring air flowtherethrough, a Constant delivery fuel supply, u fuel feed conduitconnecting said fuel supply to said engine, a primary fuel jet in saidfuel fced conduit, a return flow conduit connected to said fuel feedconduit at a point intermediate said fuel References Cited in the le 0fthis patent or the original patent UNITED STATES PATENTS Garretson Aug.14, 1945 Williams Nov. 15, 1949 Wiegand et al May 9, 1950

